ISLAMABAD/WASHINGTON (Reuters) - President Donald Trump's administration has quietly started cutting scores of Pakistani officers from coveted training and educational programs that have been a hallmark of bilateral military relations for more than a decade, U.S. officials say.

The move, which has not been previously reported, is one of the first known impacts from Trump's decision this year to suspend U.S. security assistance to Pakistan to compel it to crack down on Islamic militants.

The Pentagon and the Pakistani military did not comment directly on the decision or the internal deliberations, but officials from both countries privately criticized the move.

U.S. officials, speaking to Reuters on the condition of anonymity, said they were worried the decision could undermine a key trust-building measure. Pakistani officials warned it could push their military to further look to China or Russia for leadership training.

The effective suspension of Pakistan from the U.S. government's International Military Education and Training program (IMET) will close off places that had been set aside for 66 Pakistani officers this year, a State Department spokesperson told Reuters.

The places will either be unfilled or given to officers from other countries.

Dan Feldman, a former U.S. special representative for Afghanistan and Pakistan, called the move "very short-sighted and myopic".

"This will have lasting negative impacts limiting the bilateral relationship well into the future," Feldman told Reuters.

The State Department spokesperson, speaking on the condition of anonymity, said the IMET cancellations were valued at $2.41 million so far. At least two other programs have also been affected, the spokesperson said.

It is unclear precisely what level of military cooperation still continues outside the IMET program, beyond the top level contacts between U.S. and Pakistani military leaders.

The U.S. military has traditionally sought to shield such educational programs from political tensions, arguing that the ties built by bringing foreign military officers to the United States pay long-term dividends.

For example, the U.S. Army's War College in Carlisle, Pennsylvania, which would normally have two Pakistani military officers per year, boasts graduates including Lieutenant General Naveed Mukhtar, the current director-general of Pakistan's powerful spy agency, the Inter-Services Intelligence agency (ISI).

The War College, the U.S. Army's premier school for foreign officers, says it has hosted 37 participants from Pakistan over the past several decades. It will have no Pakistani students in the upcoming academic year, a spokeswoman said.

Pakistan has also been removed from programs at the U.S. Naval War College, Naval Staff College and courses including cyber security studies.

"LIES AND DECEIT"

In his first tweet of 2018, Trump slammed Pakistan, saying the country has rewarded past U.S. aid with "nothing but lies & deceit." Washington announced plans in January to suspend up to roughly $2 billion in U.S. security assistance to Pakistan.

But weeks later, Pakistan's foreign secretary was quoted by local media saying that Islamabad had been told the United States would continue funding IMET programs.

Officially allies in fighting terrorism, Pakistan and the United States have a complicated relationship, bound by Washington's dependence on Pakistan to supply its troops in Afghanistan but plagued by accusations Islamabad is playing a double game.

Tensions have grown over U.S. complaints that the Afghan Taliban militants and the Haqqani network that target American troops in Afghanistan are allowed to shelter on Pakistani soil.

Current and former U.S. officials said Defense Secretary Jim Mattis argued against excluding Pakistani officers from IMET courses.

"I am shocked... We worked so hard for this to be the one thing that got saved," said a former U.S. defense official, who was involved in the conversations.

The Pentagon declined to comment on internal government discussions, but Dana White, a Pentagon spokeswoman, said Mattis long believed in the value of the IMET program as a way to build relations between foreign militaries.

Pakistani Senator Mushahid Hussain, chairman of the Senate Foreign Affairs Committee, told Reuters that a U.S. decision to cut off such exchanges would be counter-productive and push Pakistan's military towards other countries.

"It is one of those silly, punitive measures that they have deployed," said Hussain, who sat next to a Chinese and Pakistani flag in his office.

Russia and Pakistan signed an agreement earlier this week that would allow for Pakistani military officers to train at Russian institutes.

Pakistan's military has ruled the country for about half of its history and traditionally seen the country's foreign policy in its domain.

IMET courses have been able to withstand poor relations between the two countries in the past, even after al Qaeda leader Osama bin Laden was killed in a U.S. Navy SEAL raid in the Pakistani town of Abbotabad in 2011.

A NATO helicopter raid killed 28 Pakistani troops later that year in a friendly fire incident on the Afghan-Pakistan border.

Feldman said that after the raid, when relations were at a low point, the United States limited large security assistance items, but made active efforts to continue the IMET program.

UNINTENDED CONSEQUENCE

In the 1990's former U.S. President George H.W. Bush refused to certify that Pakistan did not have nuclear weapons, triggering the so-called "Pressler Amendment" that required cutting off all military assistance. That included IMET courses.

"The unintended consequence was we didn't know a decade of the Pakistani military leadership as well, and therefore couldn't engage as effectively with them when we needed to," Feldman said.

Mattis, in private discussions within the government, had warned that excluding Pakistani officers from IMET courses could contribute to a similar situation in years to come, the former U.S. defense official said.

Pakistan had been the largest recipient of IMET between 2003 and 2017, according to the Security Assistance Monitor which tracks U.S. assistance.

"You can advocate for cutting off everything else and this was the one thing we were not supposed to touch," the former official said.